The present invention relates to an image reading apparatus and, particularly, to such an apparatus which can read an image at a high speed without increase in cost by moving an optical head at a high speed and scanning an image carrier by a laser beam and can be used in common for an autoradiographic image detecting system, a chemiluminescent image detecting system, an electron microscopic image detecting system and a radiographic diffraction image detecting system using a stimulable phosphor sheet, and a fluorescent image detecting system.
There is known a radiation diagnosis system comprising the steps of employing, as a detecting material for the radiation, a stimulable phosphor which can absorb and store the energy of radiation upon being irradiated therewith and release a stimulated emission whose amount is proportional to that of the received radiation upon being stimulated with an electromagnetic wave having a specific wavelength range, storing and recording the energy of radiation transmitted through an object in the stimulable phosphor contained in a stimulable phosphor layer formed on a stimulable phosphor sheet, scanning the stimulable phosphor layer with an electromagnetic wave to excite the stimulable phosphor, photoelectrically detecting the stimulated emission released from the stimulable phosphor to produce digital image signals, effecting image processing on the obtained digital image signals, and reproducing an image on displaying means such as a CRT or the like or a photographic film (see, for example, Japanese Patent Application Laid Open Nos. 55-12429, 55-116340, 55-163472, 56-11395, 56-104645 and the like).
There is also known an autoradiographic image detection system comprising the steps of employing a similar stimulable phosphor as a detecting material for the radiation, introducing a radioactive labeled substance into an organism, using the organism or a part of the tissue of the organism as a specimen, placing the specimen and a stimulable phosphor sheet formed with a stimulable phosphor layer together in layers for a certain period of time, storing and recording radiation energy in a stimulable phosphor contained in the stimulable phosphor layer, scanning the stimulable phosphor layer with an electromagnetic wave to excite the stimulable phosphor, photoelectrically detecting the stimulated emission released from the stimulable phosphor to produce digital image signals, effecting image processing on the obtained digital image signals, and reproducing an image on displaying means such as a CRT or the like or a photographic film (see, for example, Japanese Patent Publication No. 1-60784, Japanese Patent Publication No. 1-60782, Japanese Patent Publication No. 4-3952 and the like).
There is further known a chemiluminescent image detection system using as a detecting material for detecting light a stimulable phosphor which can absorb, store and record the light energy when it is irradiated with light and which, when it is then stimulated by an electromagnetic wave having a specified wavelength, can release stimulated emission whose light amount corresponds to the amount of light radiation with which it was irradiated, which comprises the steps of selectively labeling a fixed high molecular substance such as a protein or a nucleic acid sequence with a labeling substance which generates chemiluminescent emission when it contacts a chemiluminescent substance, contacting the high molecular substance selectively labeled with the labeling substance and the chemiluminescent substance, photoelectrically detecting the chemiluminescent emission in the wavelength of visible light generated by the contact of the chemiluminescent substance and the labeling substance and producing digital image signals, effecting image processing thereon, and reproducing a chemiluminescent image on a display means such as a CRT or a recording material such as a photographic film, thereby obtaining information relating to the high molecular substance such as genetic information (see, for example, U.S. Pat. No. 5,028,793, British Patent Publication GB No. 2,246,197A and the like).
There are further known an electron microscopic image detecting system and a radiographic diffraction image detecting system comprising the steps of employing, as a detecting material for an electron beam or radiation, a stimulable phosphor which can absorb and store the energy of an electron beam or radiation upon being irradiated therewith and release a stimulated emission whose amount is proportional to that of the received electron beam or radiation upon being stimulated with an electromagnetic wave having a specific wavelength range, irradiating a metal or nonmetal specimen with an electron beam and effecting elemental analysis, composition analysis or structural analysis of the specimen by detecting a diffraction image or a transmission image, or irradiating the tissue of an organism with an electron beam and detecting an image of the tissue of the organism, or irradiating a specimen with radiation, detecting a radiographic diffraction image and effecting structural analysis of the specimen (see, for example, Japanese Patent Application Laid Open No. 61-51738, Japanese Patent Application Laid Open No. 61-93538, Japanese Patent Application Laid Open No. 59-15843 and the like).
Unlike the system using a photographic film, according to these systems using the stimulable phosphor as a detecting material for an image, development, which is chemical processing, becomes unnecessary. Further, it is possible reproduce a desired image by effecting image processing on the obtained image data and effect quantitative analysis using a computer. Use of a stimulable phosphor in these processes is therefore advantageous.
On the other hand, a fluorescent image detecting system using a fluorescent substance as a labeling substance instead of a radioactive labeling substance in the autoradiographic image detecting system is known. According to this system, it is possible to study a genetic sequence, study the expression level of a gene, and to effect separation or identification of protein or estimation of the molecular weight or properties of protein or the like. For example, this system can perform a process including the steps of distributing a plurality of DNA fragments on a gel support by means of electrophoresis after a fluorescent dye was added to a solution containing a plurality of DNA fragments to be distributed, or distributing a plurality of DNA fragments on a gel support containing a fluorescent dye, or dipping a gel support on which a plurality of DNA fragments have been distributed by means of electrophoresis in a solution containing a fluorescent dye, thereby labeling the electrophoresed DNA fragments, exciting the fluorescent dye by a stimulating ray to cause it to release fluorescence, detecting the released fluorescence to produce an image and detecting the distribution of the DNA fragments on the gel support. This system can also perform a process including the steps of distributing a plurality of DNA fragments on a gel support by means of electrophoresis, denaturing the DNA fragments, transferring at least a part of the denatured DNA fragments onto a transfer support such as a nitrocellulose support by the Southern-blotting method, hybridizing a probe prepared by labeling target DNA and DNA or RNA complementary thereto with the denatured DNA fragments, thereby selectively labeling only the DNA fragments complementary to the probe DNA or probe RNA, exciting the fluorescent dye by a stimulating ray to cause it to release fluorescence, detecting the released fluorescence to produce an image and detecting the distribution of the target DNA on the transfer support. This system can further perform a process including the steps of preparing a DNA probe complementary to DNA containing a target gene labeled by a labeling substance, hybridizing it with DNA on a transfer support, combining an enzyme with the complementary DNA labeled by a labeling substance, causing the enzyme to contact a fluorescent substance, transforming the fluorescent substance to a fluorescent substance having fluorescence releasing property, exciting the thus produced fluorescent substance by a stimulating ray to release fluorescence, detecting the fluorescence to produce an image and detecting the distribution of the target DNA on the transfer support. This fluorescence detecting system is advantageous in that a genetic sequence or the like can be easily detected without using a radioactive substance.
Since the autoradiographic image detecting system, the electron microscopic image detecting system, the radiographic diffraction image detecting system, the fluorescent image detecting system and the chemiluminescent image detecting system are used for the similar purposes, it is desirable to develop an image reading apparatus which can be used in common for all of these systems.
In fact, an image reading apparatus which can be used in common for the autoradiographic image detecting system, the chemiluminescent image detecting system, the electron microscopic image detecting system and the radiographic diffraction image detecting system using a stimulable phosphor sheet, and the fluorescent image detecting system has been already developed.
An image reading apparatus used for these system is constituted so as to irradiate a stimulable phosphor layer formed on a stimulable phosphor sheet with a stimulating ray or irradiate a transfer support or a gel support containing a specimen labeled with a fluorescent substance with a stimulating ray, lead stimulated emission released from a stimulable phosphor contained in the stimulable phosphor layer upon being stimulated or fluorescence released from the fluorescent substance labeling the specimen upon being stimulated to a light detector and photoelectrically detect stimulated emission or fluorescence by the light detector. In such an image reading apparatus, since the incident direction of the stimulating ray and the direction of release of stimulated emission or fluorescence coincide with each other, an optical system is employed for separating the light path of stimulated emission or fluorescence and the light path of the stimulating ray.
As this kind of the image reading apparatus, there has been proposed an image reading apparatus constituted so as to move an optical head provided with a mirror and a convex lens in the X direction and the Y direction in order to scan a stimulable phosphor layer formed on a stimulable phosphor sheet, or a transfer support or a gel support, by a laser beam and photoelectrically detect stimulated emission or fluorescence by the steps of reflecting a laser beam emitted from a laser stimulating ray source by a dichroic mirror having a property of transmitting stimulated emission or fluorescence, further reflecting the laser beam by another mirror, thereby causing the laser beam to advance to the optical head, condensing the laser beam by the mirror provided in the optical head onto a stimulable phosphor layer formed on a stimulable phosphor sheet, or a transfer support or a gel support, making stimulated emission released from a stimulable phosphor contained in the stimulable phosphor layer upon being stimulated or fluorescence released from a fluorescent substance labeling a specimen upon being stimulated a parallel beam by the convex lens provided in the optical head, reflecting the stimulated emission or the fluorescence by the mirror provided in the optical head to be directed in the same direction as the path of the laser beam, reflecting the stimulated emission or the fluorescence by the mirror, thereby causing it to advance the dichroic mirror, and photoelectrically detecting the stimulated emission or the fluorescence transmitted through the dichroic mirror by a light detector.
There has further been proposed an image reading apparatus constituted so as to scan a stimulable phosphor layer formed on a stimulable phosphor sheet, or a transfer support or a gel support, by a laser beam by moving an optical head provided with a reflection mirror, a perforated mirror formed with a hole at the center portion thereof and a convex lens in the X direction and the Y direction and photoelectrically detect stimulated emission or fluorescence by the steps of reflecting a laser beam emitted from a laser stimulating ray source by the reflection mirror provided in the optical head, thereby leading it to the hole formed in the perforated mirror, condensing the laser beam transmitted through the hole formed in the perforated mirror by the convex lens provided in the optical head onto a stimulable phosphor layer formed on a stimulable phosphor sheet, or a transfer support or a gel support, making stimulated emission released from a stimulable phosphor contained in the stimulable phosphor layer upon being stimulated or fluorescence released from a fluorescent substance labeling a specimen upon being stimulated a parallel beam by the convex lens provided in the optical head, reflecting the stimulated emission or the fluorescence by the perforated mirror provided in the optical head to be directed in the opposite direction to the path of the laser beam, further reflecting the stimulated emission or the fluorescence by one, two or more mirrors, thereby leading it to a light detector.
However, in the former image reading apparatus, a different dichroic mirror has to be employed depending upon the wavelength of the laser beam. Therefore, in the most commonly used image reading apparatus provided with three laser stimulating ray sources (a first one for emitting a laser beam having a wavelength of 470 to 480 nm, a second one for emitting a laser beam having a wavelength of 530 to 540 nm and a third one for emitting a laser beam having a wavelength of 630 to 640 nm) so as to achieve efficient stimulation of fluorescent substances, a dichroic mirror has to be interchanged every time a different laser stimulating ray source is used, making the operation very troublesome. Further, since three kinds of dichroic mirror have to be kept on hand, the cost is inevitably increased. Moreover, although the optical head has to be moved at a high speed, for example, 2 to 3 meter/second, in order to scan a stimulable phosphor layer formed on a stimulable phosphor sheet, or a transfer support or a gel support, by a laser beam at a high speed, since the optical head is provided with a mirror and a convex lens and is relatively heavy, it is difficult to move the optical head at a high speed and, therefore, it is difficult to read an image at a high speed.
In the latter image reading apparatus, even when a laser stimulating ray source for emitting a laser beam having a different wavelength is used, it is unnecessary to interchange a dichroic mirror, and even when a plurality of laser stimulating ray sources for emitting laser beams having different wavelengths are provided, it is unnecessary to provide a dichroic mirror for each laser stimulating ray source.
However, since the optical head is provided with a reflection mirror, a perforated mirror formed with a hole at the center portion thereof and a convex lens and is therefore relatively heavy, it is difficult to move the optical head at a high speed and, therefore, it is difficult to read an image at a high speed.
It is therefore an object of the present invention to provide, without increase in cost, an image reading apparatus which can read an image at a high speed by moving an optical head at a high speed and scanning an image carrier by a laser beam and can be used in common for an autoradiographic image detecting system, a chemiluminescent image detecting system, an electron microscopic image detecting system and a radiographic diffraction image detecting system using a stimulable phosphor sheet, and a fluorescent image detecting system.
The above and other objects of the present invention can be accomplished by an image reading apparatus comprising at least one laser stimulating ray source for emitting a laser beam, a stage on which an image carrier can be placed, a light detecting means for photoelectrically detecting light released from the image carrier, and an optical head for condensing the laser beam emitted from the at least one laser stimulating ray source onto the image carrier placed on the stage and condensing light released from the image carrier to lead it to the light detecting means, the optical head being constituted to be two-dimensionally movable in a plane parallel to the stage and provided with a perforated mirror fixed in a path of the laser beam and formed with a hole at a center portion thereof, the perforated mirror being disposed so that the laser beam emitted from the at least one laser stimulating ray source can pass through the hole and light released from the image carrier and condensed by the optical head can be reflected in such a manner that a path of the light is branched off from the path of the laser beam emitted from the at least one laser stimulating ray source and advancing to the optical head.
According to the present invention, a perforated mirror formed with a hole at the center portion thereof is provided in the path of the laser beam emitted from the at least one laser stimulating ray source so that the laser beam emitted from the at least one laser stimulating ray source can pass through the hole and light released from the image carrier and condensed by the optical head can be reflected in such a manner that a path of the light is branched off from a path of the laser beam emitted from the at least one laser stimulating ray source and advancing to the optical head. As a result, the laser beam can be led to the optical head via the hole of the perforated mirror irrespective of the wavelength of the laser beam and light released from the image carrier and condensed by the optical head can be reflected by the perforated mirror irrespective of the wavelength of the light so that the light path is branched off from the path of the laser beam emitted from the at least one laser stimulating ray source and advancing to the optical head. It is therefore possible to stimulate the image carrier and read an image using laser stimulating ray sources for emitting laser beams having different wavelengths only by providing one perforated mirror. Therefore, the cost of the image reading apparatus can be reduced.
Further, according to the present invention, the optical head for scanning the image carrier by the laser beam merely serves to condense the laser beam emitted from the at least one laser stimulating ray source and condense light released from the image carrier to lead it to the light detecting means. Unlike a conventional optical head, therefore, the optical head need not be provided with a reflection mirror, a perforated mirror formed with a hole at the center portion thereof and a condensing optical system such as a convex lens. Since the weight of the optical head can be considerably reduced as compared with the conventional optical head, therefore the image carrier can be scanned by the laser beam at a high speed by two-dimensionally moving the optical head in a plane parallel to the stage, thereby markedly improving the image reading speed.
In a preferred aspect of the present invention, the optical head further includes a reflection mirror for directing the laser beam emitted from the at least one laser stimulating ray source toward the image carrier placed on the stage, and a lens system for condensing the laser beam emitted from the at least one laser stimulating ray source and reflected by the reflection mirror onto the image carrier, making light released from the image carrier a parallel beam and causing it to impinge on the reflection mirror, the reflection mirror being constituted so as to reflect the light released from the image carrier and made a parallel beam by the lens system toward the perforated mirror.
According to this preferred aspect of the present invention, since, unlike a conventional optical head, the optical head need not be provided with a reflection mirror, a perforated mirror formed with a hole at the center portion thereof and a condensing optical system such as a convex lens but is provided with only the reflection mirror and the lens system, the weight of the optical head can be markedly reduced as compared with the conventional optical head. Therefore, the image carrier can be scanned by the laser beam at a high speed by two-dimensionally moving the optical head in a plane parallel to the stage, thereby markedly improving the image reading speed.
In another preferred aspect of the present invention, the optical head further includes a concave mirror for directing the laser beam emitted from the at least one laser stimulating ray source toward the image carrier, condensing it onto the image carrier and reflecting light released from the image carrier toward the perforated mirror so as to be made a parallel beam.
According to this preferred aspect of the present invention, since the optical head is provided with only the concave mirror for directing the laser beam emitted from the at least one laser stimulating ray source toward the image carrier, condensing it onto the image carrier and reflecting light released from the image carrier toward the perforated mirror so as to be made a parallel beam, the weight of the optical head can be markedly reduced as compared with the conventional optical head including a reflection mirror, a perforated mirror and a convex lens. Therefore, the image carrier can be scanned by the laser beam at a high speed by two-dimensionally moving the optical head in a plane parallel to the stage, thereby markedly improving the image reading speed.
In a further preferred aspect of the present invention, the lens system is constituted by an aspherical lens.
In another preferred aspect of the present invention, the lens system is constituted by a convex lens.
In a further preferred aspect of the present invention, the image reading apparatus includes two or more laser stimulating ray sources for emitting laser beams having different wavelengths from each other.
According to this preferred aspect of the present invention, since the image reading apparatus includes two or more laser stimulating ray sources for emitting laser beams having different wavelengths from each other, images carried in image carriers containing specimens labeled with fluorescent substances which can be efficiently excited by laser beams whose wavelengths are different from each other and a stimulable phosphor layer formed on a stimulable phosphor sheet recording locational information regarding a radioactive labeling substance can be read by a single image reading apparatus with high efficiency.
In a further preferred aspect of the present invention, the image reading apparatus further includes a condensing optical system for leading the light released from the image carrier, condensed by the optical head and reflected by the perforated mirror to the light detecting means.
In the case where a fluorescent image carried in a transfer support or a gel support, particularly an agarose gel support, is to be read, a fluorescent substance is distributed in the depth direction of the support and light releasing points are distributed in the depth direction of the support when the fluorescent substance is stimulated. Therefore, when it is attempted to use the optical head to condense fluorescence released from a transfer support or a gel support onto the light detecting means, the beam of fluorescence diverges and fluorescence released from the deep portions of a transfer support or a gel support does not impinge on the light detecting means and is not detected by the light detecting means. It is therefore difficult to read a fluorescent image with markedly improved sensitivity. However, according to this preferred aspect of the present invention, since the image reading apparatus further includes a condensing optical system for leading the light released from the image carrier, condensed by the optical head and reflected by the perforated mirror to the light detecting means, the light detecting means can reliably detect fluorescence released from the deep portions of a transfer support or a gel support. It is therefore possible to read a fluorescent image with markedly improved sensitivity.
In a further preferred aspect of the present invention, the image reading apparatus further includes a stimulating ray cut filter unit provided with two or more stimulating ray cut filters each having a property of cutting off light having a wavelength of the laser beam emitted from one of the laser stimulating ray sources among the two or more laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted from the one of the laser stimulating ray sources and the stimulating ray cut filter unit is constituted to be movable so that one of the two or more stimulating ray cut filters is selectively located in a path of light released from the image carrier, condensed by the optical head and reflected by the perforated mirror.
According to this preferred aspect of the present invention, the image reading apparatus further includes a stimulating ray cut filter unit provided with two or more stimulating ray cut filters each having a property of cutting off light having a wavelength of the laser beam emitted from one of the laser stimulating ray sources among the two or more laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted from the one of the laser stimulating ray sources, and the stimulating ray cut filter unit is constituted to be movable so that one of the two or more stimulating ray cut filters is selectively located in a path of light released from the image carrier, condensed by the optical head and reflected by the perforated mirror. It is therefore possible to prevent noise caused by detecting a stimulating ray by the light detecting means from being generated in the image data.
In a further preferred aspect of the present invention, the condensing optical system is constituted so as to lead light transmitted through the stimulating ray cut filter unit to the light detecting means.
In another preferred aspect of the present invention, the condensing optical system is constituted so as to condense light released from the image carrier, condensed by the optical head and reflected by the perforated mirror onto the stimulating ray cut filter unit, thereby leading it to the light detecting means.
In a further preferred aspect of the present invention, the image reading apparatus further includes a stimulating ray cut filter module provided with a stimulating ray cut filter having a property of cutting off light having a wavelength of the laser beam emitted from one of the laser stimulating ray sources among the two or more laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted from the one of the laser stimulating ray sources, and the stimulating ray cut filter module is constituted to be exchangeable and locatable in a path of light released from the image carrier, condensed by the optical head and reflected by the perforated mirror.
According to this preferred aspect of the present invention, the image reading apparatus further includes a stimulating ray cut filter module provided with a stimulating ray cut filter having a property of cutting off light having a wavelength of the laser beam emitted from one of the laser stimulating ray sources among the two or more laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted from the one of the laser stimulating ray sources and the stimulating ray cut filter module is constituted to be exchangeable and locatable in a path of light released from the image carrier, condensed by the optical head and reflected by the perforated mirror. It is therefore possible to prevent noise caused by detecting a stimulating ray by the light detecting means from being generated in the image data by selecting an appropriate stimulating ray cut filter module in accordance with the wavelength of the laser beam to be used for stimulating a labeling substance and locating the thus selected stimulating ray cut filter module in the path of light released from the image carrier, condensed by the optical head and reflected by the perforated mirror.
In a further preferred aspect of the present invention, the condensing optical system is constituted so as to lead light transmitted through the stimulating ray cut filter module to the light detecting means.
In another preferred aspect of the present invention, the condensing optical system is constituted so as to condense light released from the image carrier, condensed by the optical head and reflected by the perforated mirror onto the stimulating ray cut filter module, thereby leading it to the light detecting means.
In a further preferred aspect of the present invention, the image reading apparatus further includes a stimulating ray cut filter module provided with a stimulating ray cut filter having a property of cutting off light having a wavelength of the laser beam emitted from one of the laser stimulating ray sources among the two or more laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted from the one of the laser stimulating ray sources and a condensing optical system for leading light released from the image carrier, condensed by the optical head and reflected by the perforated mirror to the light detecting means, and the stimulating ray cut filter module is constituted to be exchangeable and locatable in a path of light released from the image carrier, condensed by the optical head and reflected by the perforated mirror.
In the case where a fluorescent image carried in a transfer support or a gel support, particularly an agarose gel support, is to be read, a fluorescent substance is distributed in the depth direction of the support and light releasing points are distributed in the depth direction of the support when the fluorescent substance is stimulated. Therefore, when it is attempted to use the optical head to condense fluorescence released from a transfer support or a gel support onto the light detecting means, the beam of fluorescence diverges and fluorescence released from the deep portions of a transfer support or a gel support does not impinge on the light detecting means and is not detected by the light detecting means. It is therefore difficult to read a fluorescent image with markedly improved sensitivity. However, according to this preferred aspect of the present invention, the image reading apparatus further includes a stimulating ray cut filter module provided with a stimulating ray cut filter having a property of cutting off light having a wavelength of the laser beam emitted from one of the laser stimulating ray sources among the two or more laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted from the one of the laser stimulating ray sources and a condensing optical system for leading light released from the image carrier, condensed by the optical head and reflected by the perforated mirror to the light detecting means, and the stimulating ray cut filter module is constituted to be exchangeable and locatable in the path of light released from the image carrier, condensed by the optical head and reflected by the perforated mirror. As a result, the light detecting means can reliably detect fluorescence released from the deep portions of a transfer support or a gel support. It is therefore possible to read a fluorescent image with markedly improved sensitivity. On the other hand, in the case of stimulating a stimulable phosphor contained in a stimulable phosphor layer formed on a stimulable phosphor sheet by a laser beam, since stimulated emission is released from a portion in the vicinity of the surface of the stimulable phosphor layer formed on the stimulable phosphor sheet, the optical head enables the light detecting means to reliably detect the stimulated emission, whereas if stimulated emission should be led to the light detecting means using the condensing optical system, the beam of the stimulated emission would diverge and a part of the stimulated emission might not be detected by the light detecting means. However, according to this preferred aspect of the present invention, the stimulating ray cut filter module is constituted to be exchangeable. Therefore, when an image of a radioactive labeling substance recorded in a stimulable phosphor layer formed on a stimulable phosphor sheet is read, the light detecting means can reliably detect stimulated emission released from the stimulable phosphor layer formed on the stimulable phosphor sheet by replacing the stimulating ray cut filter module having a condensing optical system for a stimulating ray cut filter module having no condensing optical system. It is therefore possible to read an image of a radioactive labeling substance with markedly improved sensitivity.
In a further preferred aspect of the present invention, the condensing optical system is constituted so as to lead light transmitted through the stimulating ray cut filter to the light detecting means.
In another preferred aspect of the present invention, the condensing optical system is constituted so as to condense light released from the image carrier, condensed by the optical head and reflected by the perforated mirror onto the stimulating ray cut filter, thereby leading it to the light detecting means.
In a further preferred aspect of the present invention, the condensing optical system is constituted by a convex lens.
According to this preferred aspect of the present invention, since the condensing optical system is constituted by a convex lens, the stimulating ray cut filter module can be made compact, thereby enabling the stimulating ray cut filter module to be easily handled and making the image reading apparatus small.
In another preferred aspect of the present invention, the condensing optical system is constituted by a concave mirror.
In a further preferred aspect of the present invention, the image reading apparatus includes a first light detecting means and a second light detecting means for photoelectrically detecting light emitted from the image carrier, and a stimulating ray cut filter module provided with a first stimulating ray cut filter having a property of cutting off light having a wavelength of the laser beam emitted from one of the laser stimulating ray sources among the two or more laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted from said one of the laser stimulating ray sources, a second stimulating ray cut filter having a property of cutting off light having a wavelength of the laser beam emitted from a laser stimulating ray source different from said one of the laser stimulating ray sources among the two or more laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted from the laser stimulating ray source different from said one of the laser stimulating ray sources, a dichroic mirror having a property of reflecting light having a wavelength longer than the wavelength of the laser beam emitted from said one of the laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted from the laser stimulating ray source different from said one of the laser stimulating ray sources, a first condensing optical system for condensing light released from the image carrier and reflected by the dichroic mirror onto the first light detecting means, and a second light detecting means for condensing light released from the image carrier and transmitted through the dichroic mirror onto the second light detecting means, the stimulating ray cut filter module being constituted to be exchangeable and locatable in a path of the light released from the image carrier, condensed by the optical head and reflected by the perforated mirror.
In the case where a fluorescent image carried in a transfer support or a gel support, particularly an agarose gel support, is to be read, a fluorescent substance is distributed in the depth direction of the support and light releasing points are distributed in the depth direction of the support when the fluorescent substance is stimulated. Therefore, when it is attempted to use the optical head to condense fluorescence released from a transfer support or a gel support onto the light detecting means, the beam of fluorescence diverges and fluorescence released from the deep portions of a transfer support or a gel support does not impinge on the light detecting means and is not detected by the light detecting means. It is therefore difficult to read a fluorescent image with markedly improved sensitivity. However, according to this preferred aspect of the present invention, the image reading apparatus includes a first light detecting means and a second light detecting means for photoelectrically detecting light emitted from the image carrier, and a stimulating ray cut filter module provided with a first stimulating ray cut filter having a property of cutting off light having a wavelength of the laser beam emitted from one of the laser stimulating ray sources among the two or more laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted from said one of the laser stimulating ray sources, a second stimulating ray cut filter having a property of cutting off light having a wavelength of the laser beam emitted from a laser stimulating ray source different from said one of the laser stimulating ray sources among the two or more laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted from the laser stimulating ray source different from said one of the laser stimulating ray sources, a dichroic mirror having a property of reflecting light having a wavelength longer than the wavelength of the laser beam emitted from said one of the laser stimulating ray sources and transmitting light having a wavelength longer than the wavelength of the laser beam emitted form the laser stimulating ray source different from said one of the laser stimulating ray sources, a first condensing optical system for condensing light released from the image carrier and reflected by the dichroic mirror onto the first light detecting means, and a second light detecting means for condensing light released from the image carrier and transmitted through the dichroic mirror onto the second light detecting means, the stimulating ray cut filter module being constituted to be exchangeable and locatable in the path of the light released from the image carrier, condensed by the optical head and reflected by the perforated mirror. As a result, the first light detecting means and the second light detecting means can reliably detect fluorescence released from the deep portions of a transfer support or a gel support. It is therefore possible to read a fluorescent image with markedly improved sensitivity. On the other hand, in the case of stimulating a stimulable phosphor contained in a stimulable phosphor layer formed on a stimulable phosphor sheet by a laser beam, since stimulated emission is released from a portion in the vicinity of the surface of the stimulable phosphor layer formed on the stimulable phosphor sheet, the optical head enables the first light detecting means or the second light detecting means to reliably detect the stimulated emission, whereas if stimulated emission should be led to the first light detecting means or the second light detecting means using the condensing optical system, the beam of the stimulated emission would diverge and a part of the stimulated emission might not be detected by the first light detecting means or the second light detecting means. However, according to this preferred aspect of the present invention, the stimulating ray cut filter module is constituted to be exchangeable. Therefore, when an image of a radioactive labeling substance recorded in a stimulable phosphor layer formed on a stimulable phosphor sheet is read, the first light detecting means or the second light detecting means can reliably detect stimulated emission released from the stimulable phosphor layer formed on the stimulable phosphor sheet by replacing the stimulating ray cut filter module having a condensing optical system for a stimulating ray cut filter module having no condensing optical system. It is therefore possible to read an image of a radioactive labeling substance with markedly improved sensitivity.
Further, according to this preferred aspect of the present invention, it is possible to simultaneously irradiate an image carrier carrying a fluorescent image of a specimen selectively labeled with two kinds of fluorescent substances by laser beams emitted from two laser stimulating ray sources, thereby stimulating the two kinds of fluorescent substances capable of being efficiently stimulated by light of different wavelength by two laser beams having different wavelengths, and simultaneously detect fluorescence released from the two kinds of fluorescent substances using the first light detecting means and the second light detecting means to thereby obtain two fluorescent images corresponding to the respective fluorescent substances.
In a further preferred aspect of the present invention, the first condensing optical system is constituted so as to lead light transmitted through the first stimulating ray cut filter to the first light detecting means.
In another preferred aspect of the present invention, the first condensing optical system is constituted so as to condense light released from the image carrier and reflected by the dichroic mirror onto the first stimulating ray cut filter, thereby leading it to the first light detecting means.
In a further preferred aspect of the present invention, the second condensing optical system is constituted so as to lead light transmitted through the second stimulating ray cut filter to the second light detecting means.
In another preferred aspect of the present invention, the second condensing optical system is constituted so as to condense light released from the image carrier and transmitted through the dichroic mirror onto the second stimulating ray cut filter, thereby leading it to the second light detecting means.
In a further preferred aspect of the present invention, the first condensing optical system is constituted by a convex lens.
According to this preferred aspect of the present invention, since the first condensing optical system is constituted by a convex lens, the stimulating ray cut filter module can be made compact, thereby enabling the stimulating ray cut filter module to be easily handled and making the image reading apparatus small.
In a further preferred aspect of the present invention, the second condensing optical system is constituted by a convex lens.
According to this preferred aspect of the present invention, since the second condensing optical system is constituted by a convex lens, the stimulating ray cut filter module can be made compact, thereby enabling the stimulating ray cut filter module to be easily handled and making the image reading apparatus small.
In a further preferred aspect of the present invention, the first condensing optical system is constituted by a concave mirror.
In a further preferred aspect of the present invention, the second condensing optical system is constituted by a concave mirror.
In a preferred aspect of the present invention, the at least one laser stimulating ray source includes at least one built-in laser stimulating ray source and the image reading apparatus further includes an external laser stimulating ray source unit including a single case, at least two external laser stimulating ray sources accommodated in the case, at least two optical fiber members each for leading a laser beam emitted from one of the at least two external laser stimulating ray sources to a main body of the image reading apparatus, and a single protective tube member for covering and protecting the at least two optical fiber members.
According to this preferred aspect of the present invention, the external laser stimulating unit including at least two laser stimulating ray sources accommodated in the case and laser beams emitted from the at least two laser stimulating ray sources are led via separate optical fiber members to the main body of the image reading apparatus and the at least two optical fiber members are covered and protected by a single protective tube member. Therefore, the cost of the image reading apparatus can be considerably reduced as compared with an image reading apparatus in which external laser stimulating ray sources are accommodated in separate cases and laser beams emitted from the external laser stimulating ray sources are led to the main body of the image reading apparatus by separate optical fiber members and covered by separate protective tube members.
In a further preferred aspect of the present invention, the image carrier includes a support for carrying a fluorescent image produced by a fluorescent image detection system.
In a further preferred aspect of the present invention, the image carrier includes a stimulable phosphor sheet selected from a group consisting of a stimulable phosphor sheet for carrying an autoradiographic image, a stimulable phosphor sheet carrying an electron microscopic image, a stimulable phosphor sheet carrying a radiographic diffraction image and a stimulable phosphor sheet carrying a chemiluminescent image.
In the present invention, the stimulable phosphor usable for recording an autoradiographic image, an electron microscopic image or a radiation diffraction image in a stimulable phosphor sheet may be of any type insofar as it can store radiation energy or electron beam energy and can be stimulated by an electromagnetic wave to release the radiation energy or the electron beam energy stored therein in the form of light. More specifically, preferably employed stimulable phosphors include alkaline earth metal fluorohalide phosphors (Ba1xe2x88x92x, M2+x)FX:yA (where M2+ is at least one alkaline earth metal selected from the group consisting of Mg, Ca, Sr, Zn and Cd; X is at least one element selected from the group consisting of Cl, Br and I, A is at least one element selected from the group consisting of Eu, Tb, Ce, Tm, Dy, Pr, He, Nd, Yb and Er; x is equal to or greater than 0 and equal to or less than 0.6 and y is equal to or greater than 0 and equal to or less than 0.2.) disclosed in U.S. Pat. No. 4,239,968, alkaline earth metal fluorohalide phosphors SrFX:Z (where X is at least one halogen selected from the group consisting of Cl, Br and I; Z is at least one Eu and Ce.) disclosed in Japanese Patent Application Laid Open No. 2-276997, europium activated complex halide phosphors BaFXxNaXxe2x80x2:aEu2+ (where each of X or Xxe2x80x2 is at least one halogen selected from the group consisting of Cl, Br and I; x is greater than 0 and equal to or less than 2; and y is greater than 0 and equal to or less than 0.2.) disclosed in Japanese Patent Application Laid Open No. 59-56479, cerium activated trivalent metal oxyhalide phosphors MOX:xCe (where M is at least one trivalent metal selected from the group consisting of Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Bi; X is at least one halogen selected from the group consisting of Br and I; and x is greater than 0 and less than 0.1.) disclosed in Japanese Patent Application laid Open No. 58-69281, cerium activated rare earth oxyhalide phosphors LnOX:xCe (where Ln is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; X is at least one halogen selected from the group consisting of Cl, Br and I; and x is greater than 0 and equal to or less than 0.1.) disclosed in U.S. Pat. No. 4,539,137 and europium activated complex halide phosphors MIIFXaMIXxe2x80x2bMxe2x80x2IIXxe2x80x32cMIIIXxe2x80x2xe2x80x33xA:yEu2+ (where MII is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; MI is at least one alkaline metal selected from the group consisting of Li, Na, K, Rb and Cs; Mxe2x80x2II is at least one divalent metal selected from the group consisting of Be and Mg; MIII is at least one trivalent metal selected from the group consisting of Al, Ga, In and Ti; A is at least one metal oxide; X is at least one halogen selected from the group consisting of Cl, Br and I; each of Xxe2x80x2, Xxe2x80x3 and Xxe2x80x2xe2x80x3 is at least one halogen selected from the group consisting of F, Cl, Br and I; a is equal to or greater than 0 and equal to or less than 2; b is equal to or greater than 0 and equal to or less than 10xe2x88x922; c is equal to or greater than 0 and equal to or less than 10xe2x88x922; a+b+c is equal to or greater than 10xe2x88x922; x is greater than 0 and equal to or less than 0.5; and y is greater than 0 and equal to or less than 0.2.) disclosed in U.S. Pat. No. 4,962,047.
In the present invention, the stimulable phosphor usable for recording a chemiluminescent image in a stimulable phosphor sheet may be of any type insofar as it can store the energy of light in the wavelength band of visible light and can be stimulated by an electromagnetic wave to release in the form of light the energy of the light in the wavelength band of visible light stored therein. More specifically, preferably employed stimulable phosphors include at least one selected from the group consisting of metal halophosphates, rare-earth-activated sulfide-host phosphors, aluminate-host phosphors, silicate-host phosphors, fluoridehost phosphors and mixtures of two, three or more of these phosphors. Among them, rare-earth-activated sulfide-host phosphors are more preferable and, particularly, rare-earth-activated alkaline earth metal sulfide-host phosphors disclosed in U.S. Pat. Nos. 5,029,253 and 4,983,834 are most preferable.
The above and other objects and features of the present invention will become apparent from the following description made with reference to the accompanying drawings.